Synchronizing clutch



Dec. 10, 1940.

H. slNcLAlR SYNCHRONIZING CLUTCH Filed Jan. y3o, 1940 2 Sheets--Sheetl l Ens Patented Dec. 10, 1940 UNITED STATES PATENT oFFlcs A Harold Sinclair, Kensington, London, England Application January 30, 1940, Serial No. 316,307I y ,In Great Britain January 26, 1939.

11 Claims.

This invention relates to mechanical coupling means of the synchronizing coupling type for conveying or preventing rotary motion, suchv forv instance as the Legge synchro-coupling, examples of which are described. in Patent No. 1,862,188 of Norton Legge and the specification of my patent application Serial No. 169,973 iledv October 20, 1937.

The type of synchronizing coupling means with which this invention is concerned comprises a`toothed first member (which may be the driving member or a driven member or a stop member), a second member (which may be the driven or stop member, or the driving member respectively), an intermediate member so engaged with the second member as to be constrained to move helically with respect thereto in consequence of relative rotation between the intermediate and second members, the intermediatev member having teeth engageable with the teeth on the rst member, and a subsidiary ratchet drive adapted to couple together the first and intermediate members and so arranged as to eiect engagement of the teeth of the rst and intermediate members without clashing on relative angular displacement of the first and second members in one sense. In the preferred construction the subsidiary ratchet drive includes a pawl displaceably mounted on the first member or on the intermediate member and co-operating with teeth-preferably the said teeth-on the intermediate member or the rst member respectively.

In the normal operationof such synchronizing coupling means, the torque load transmitted by the subsidiary ratchet drive is no more than that required to displace the intermediate member on the second member, sincethe arrangement is such' that, during engagement together of the teeth on the iirst and intermediate meinbers, the ratchet drive becomes inoperative before these teeth are fully engaged.

Under certaincircumstances, however, as for example when a plurality of Legge synchrocouplings or a double Legge synchro-coupling is used as gear-selecting clutch means inchangespeed gearing, abnormal conditions may arise, such as the involuntary reversal of the input or the output shaft of the'gearing during operating of the gear-changing control means, which cause an unduly high torque to be applied to the subsidiary ratchet drives, and an object of this invention is to provide an improved construction which eliminates any risk of damage due to excessive torque on the subsidiary ratchet drive.

According to this invention in synchronizing coupling means of the type hereinbefore set forth the subsidiary ratchet drive comprises means which enable it to automatically slip in consequence of the application of an excessive torque through it and which, when the conditions producing such excessive torque no longer exist, lleave the ratchet drive in condition to perform its normal synchronizing function.

I n the preferred construction 'in accordance with this invention, an abutting surface onAthe nose of the pawl of the subsidiary ratchet drive, or the tooth portions with which this nose cooperates, or both of these surfaces, are inclined in such a manner that excessive torque loading transmitted through the pawl will displace it out of engagement with the tooth. When the pawl ison a rotatable member, the pawl is preferably biased towards its engaging position by a relatively light spring and so arranged that its 20 bias is increased by the e'ect'of centrifugal force upon rotation of the member on which the paw is mounted.

The invention will be further described by way of example with reference to the accompanying 25 drawings, in which:

Fig. 1 is a sectional side elevation of a planetary two-speed gear, a part bein'g shown in section on the line I-I in Fig. 2,

Fig. 2 is a section to a larger scale on the line 30 2 2 in Fig. 1,

Fig. 3 is an end elevation of a pawl to a still larger scale,

Fig. 4 is a section of part of a modif-led arrangement of synchronous coupling, taken on 35 the line 4-4 in Fig. 5.

Fig. 5 is a section on the line 5-5 in Fig. 4,

Fig. 6 is a developed view of the right-hand coupling part of Fig. 5,

, Fig. '7 is a sectional end elevation of part of a o further modcation, and

Fig. 8 shows a modification of the pawl arrangement shown in Fig. 3.

The gear shown in Fig. 1 is suitable for use between an internal-combustion engine and another change-speed gear. The input shaft III of the gear passes through a sleeve II on which is. formed a sun pinion I2. A planet carrier I3 is fixed to the input shaft and carries planet wheels such as I4. An annulus gear drum I5 is 50 fixed to the output shaft I6. A drum Il is provided with for example forty-eight teeth consisting of sixteen uniformly-spaced full-depth teeth IBA and thirty-two shallow teeth I8 cut back to the pitch circle. This drum Il is fixed to the input shaft III and forms the first member of a double Legge synchro-coupling. The

second member of this coupling is formed by the sun sleeve II, which has a right-handed screw 5 thread I9 of steep pitch on its exterior. The intermediate member of the synchro-coupling is a nut 29 engaged on this screw thread and provided with a flange 2| having on its periphery forty-eight Jaw-clutch teeth 22 engageable. when l the nut is in its extreme left-hand position (as viewed in Fig. 1), with the teeth I8 and I8A on the input drum I1, and. when the nut is in its extreme right-hand position, with forty-eight jaw clutch teeth 28 on a xed ring 24 forming l5 the reaction element of the gearing. On the front of the flange 2I are mounted three uniformly-spaced pawls 28 journalled on pins 28. Each pawl has a nose 21 which points forwards (i. e. in the normal direction of rotation of the 0 input shaft) and which is biased outwards by a light spring 28. Each pawl also has a tail 28 which is adapted to bear on the body of the nut 28 and thus limit the outward displacement of the nose. The pawls are so shaped that 4their noses are substantially heavier than their tails. When the nut ls in its mid position as shown in Fig. l, the pawls 28 are in register with the deep teeth I8A and are thus in a position to cooperate with them (as shown in Fig. 2). 3 The noses 21 of the pawls are provided with abutting surfaces 88 which are inclined to tangents to their path of displacement about the pins 28, the inclination being such that the pawls will slip inwards out of engagement with any tooth IIA on the occurrence of an excessive torque through them. In the example shown, when the nose of a pawl 2S is engaged behind a tooth I8A, theabutting surface 88 preferably lies at an angle A (Fig. 3) of between '17 and 'I9 degrees to the line of action 4I of the pawl, i. e. a line joining the axis of the pin 28 to the point of contact of the surface 88 and the tooth I8A. It is convenient to position the pin 28 so that the surface 89 lies at an angle B of between 38 and 40 48 degrees with a line 42 bisecting the tooth I8A and radiating from the axis of rotation of 'the gear.

On the rear of the flange 2l are mounted pawls 82 the noses 88 of which trail with respect 80 to the forward direction of rotation. 'I'hese pawls may be shaped in known manner.

` The nut is capable of being locked in both of its end positions by means of a sleeve 84 adapted to be slid axially by preselector control means including a slidable rod 85 and a yoke 88 resiliently coupled thereto. The yoke 88 has a tubular boss 80 provided at its ends with inturned flanges 9i and 92 which normally register with collars on the rod 85.- These collars are in the form of 00 snap rings 83 and 84 engaged in grooves 88 and 89 in this rod. Washers 88 and 88, which are an accurate sliding fit on the rod 88 and within the boss 88, are urged apart by a relatively light compression spring 81 to cooperate withthe flanges 65 8| and 82 and with the collars 88 and 84. Illhe rod 88 is provided with two notches 88 and 9| cooperating with a locating plunger 82 slidable in a bore in the gear case 84 'and loaded by a relatively stiff compression spring 88. The locking sleeve 84 has internal axial splines 81 engaged with splines 88 on the nut and engageable, only when the nut is in its extreme right-hand position, with splines 89 on the sleeve II. The locking sleeve is provided also with splines 48 which are staggered circumferentially with respect to the splines 81 and are engageable with the splines 39 only when the nut is in its extreme left-hand position.

This gear operates as'follows. The normal, forv ward direction of rotation of the shafts III and 5 I8 ls indicated by arrows in Figs. 1 and 2. On direct drive (low speed gear) the nut 20 and the locking sleeve 84 will be in their extreme lefthand positions, the teeth 22 being engaged with the teeth I8 and I8A, the splines 48 on the sleeve 10 84 engaged with the splines 89 on the sleeve II, and the locating plunger 92 engaged in the notch 88. Under these conditions the planetary gear train rotates as a unit.

In order to change to high speed while the gear 15 is running. the rod 88 is shifted to the right so as to engage the plunger 82 in the notch 9|. The yoke 88 and the locking sleeve 84 are consequently shifted tothe position shown in Fig. 1, but since the splines 81 do not register with the 2 gaps between the splines 88 while the nut is not in its extreme right-hand position. the parts 88 and 84 are thereby -prevented from shifting further to the right. Consequently the collar 94 25 slides the washer 88 to the right relatively to the boss 88, compressing the spring 81 against the washer 88 which is retained by the flange 9|. The engine is now retarded. Owing to the action of the planetary gear train and the inertia of the parts driven by the output shaft I8, the speed of the sleeve II drops faster than that of the teeth I8 and IIA rotating with the input shaft I0. The nut is accordingly caused, by the reaction torque load on the screw thread I9 under over- 35 running conditions, to move to the right until the teeth 22 are disengaged from the teeth I8 and I8A. The pawls 28 and 82 now ratchet over the teeth I8, I8A and 28 respectively, and as soon as the engine speed falls to a value such that the sun sleeve II begins to rotate backwards, i. e., opo positely to the direction denoted by the arrows in Figs. 1 and 2, a pawl 82 engages a tooth 23 and establishes through the screw thread I9 an overrimning torque load which causes the nut to move to its extreme right hand position, the pawls a 82 being so positioned as to cause engagement of the teeth 22 and 28 without clashing. The shafts I8 and I8 are thus synchronized in the overdrive ratio under the overrunning torque. As such synw chronism is established by the full interengagement of the teeth 22 and 28, the splines 81 and 89 come into meshing register and the spring 81 op-l erates to move the locking sleeve to the right to engage the splines 81 and 89 and thereby lock the u nut. The engine is now accelerated again, and since the nut 28 is prevented by the locking sleeve 84 from moving to the left under the influence of the torque reaction on the screw thread I9. under driving conditions, the 'teeth 22 and 28 remain engaged together and the overdrive ratio is kept engaged.

In order to change to low speed, the rod is shifted to the left to disengage the locating plunger 82 from the notch 8| and engage it in the es notch 88. Since driving torque reaction maintains the engaged splines 81 and 88 under load, the friction due to such load prevents the locking sleeve 84 from being. shifted to the left so that the collar u slides the washer as to the 70 left relatively to the boss 88, compressing the spring 81 against the washer 88 which is retained by the flange 82. Next the engine is momentarily retarded to eliminate the torque from the locking sleeve, which thereupon moves to the position 15 shown in Fig. 1, under the iniiuence of the spring 81. As the engine accelerates again. the sleeve II begins to rotate forwards, i. e., in the direction indicated by the arrows in Figs. l and 2, and the nut 20 is moved to the left by the reaction torque load on the screw thread I9 under driving conditions, until the teeth 22 disengage from the teeth 23. The teeth 23 and IBA now ratchet over the pawls 32 and 25 respectively, and, as soon as the sleeve II begins to rotate faster than the shaft I0. a pawl 25 engages a tooth IBA, causing the nut to move to its extreme left-hand position, the pawls 25 being so positioned as to cause engagement of the teeth 22 with the teeth I8 and IBA without clashing, whereupon the splines l are brought into register with the gaps between the splines 39, so that the locking sleeve 34 moves to the left, under the influence of thespring 81,

locking the gear in .direct drive.

Now, assume that the nut 20 is in its extreme left-hand position (direct drive), thatv the engine and gearing are at rest, and that the selector rod 35 is moved tothe right to'preselect the highspeed gear. The locking sleeve 34 will move to the position shown in Fig. 1, unlocking the nut. Assume further that an attempt is made to start the engine and that, owing for example to preignition, it rotates backwards, i. e., counter to the direction indicated by the arrows in Figs. 1 and 2, for one or two revolutions. When the shaft Ill rotates backwards, the shaft I6 being at rest, the

. sleeve II is caused to rotate backwards faster than the shaft I0 and the drum I'I xed to this shaft,

with the result that the nut 20, which is unlocked,

is moved to the right along the screw thread I9 by the co-operation of the teeth I8 and |8A on the drum with the teeth 22. When the nut reaches substantially the position shown in Fig. 1, a pawl 32 engages a tooth 23 and thereby stops rotation of the nut while a pawl 25 is still engaged with a tooth IBA. If these pawls were incapable of disengagement under these conditions, they would transmit the whole of the reverse torque from the shaft I0 to the fixed ring 24 andvwould thus be liable to be broken. However, owing to the Obliquity of the abutting surfaces 30 of the noses of the pawls 25, these pawls disengage automatically from the teeth IBA as soon as the torque load on them becomes excessive, and in this way risk of damage is eliminated.

In the course of gear changing during normal running, the nut 20 will be rotating when the pawls 25 are required to engage the teeth IBA, and since these pawls are nose-heavy, centrifugal force will assist the action of the pawl springs 28 and eliminate any risk of failure of the pawls to operate properly under their normal working load.

As an alternative the subsidiary ratchet drive path may include a ratchet device which is in` capable of disengagement on overload and which is connected in series with a subsidiary clutch device a'dapted to slip under overload and to be restored to its normalA driving condition only when its driving and driven elements are in an angular relationship such that the subsidiary ratchet drive is capable of synchronizing the coupling teeth.

Such an arrangement is shown in Figs. 4, and 6, in which parts correspondingy to equivalent parts in Fig. 1 are given the reference numerals of the latter increased by |00. In this modification each pawl |25 has an abutting surface |30 which is tangential to its path of displacement.about 75 the pawl pivot pin |26, so that there is no tendency for the pawl to slip out of engagement with any tooth ||8A on the occurrence of excessive torque. T'he pawl is provided with a step 50 adapted to engage a stop 5| formed in a ring 52 which is providedk with a recess 53 shaped to receive the pawl.

and the pawl spring |28. An annular cover plate 54 held by the pawl pins |26 retains the pawls and.

pawl springs in the recesses 53. The ring 52 is provided with zig-zag serrations 55 normally held in mesh with similar serrations 56 on the nut flange I2I by the agency of a spring washer 51 placed between the ring 52 and a washer 50 held by a snap ring 59 engaged in the nut |20. The serrationshaveV a pitch equal to the pitch of the teeth |22 and are so disposed thatthe pawls are normally-properly located in the circumferential direction with respect to the teeth |22. Should however a suillcient overload accidentally come on a pawl |25, the serrations will ride over each other, the ring 52 moving to the left (as seen in Figs. 5 and 6) and rotating relatively to the nut |20. As soon as the overload is relieved, the spring 51 ensures that the ring 52 returns to its normal position relative to the nut with the serrations fully meshed together, so that the pawls are again ready to eiect synchronous engagement of the teeth I8 and I`|8A with the teeth |22.

As a further alternative, the subsidiary ratchet drive may comprise a pawl which is displaceable in the circumferential. direction relatively to the part on which it is mounted and against the iniiuence of a spring which normally retains the pawl in `engagement with a stop limiting such displacement in the direction in which the pawl nose faces, and means c'o-operating with the pawl for retracting it in consequence of its circumferential displacement in the other direction. Thus in Fig. 7 the pawl 225, which is accommodated in a recess 253 in the nut 220 and which serves to guide jaw-clutch teeth (not shown) into synchronous engagement with the teeth 222 on the nut, is provided With a slotted hole 60 through which passes the pivot pin 228. A plunger 6|, loaded by a strong compression spring 62 and slidable in a bore 63 in the nut 220, engages the rear end of the pawl at a position offset with respect to the slot 60 in such a manner that the pawl is kept at the limit of its range oi' circumferential displacement at which the abutting surface 230 on the'nose is positioned to cause synchronous engagement of the jawv clutch 'in the nut and the pin 65, riding up the oblique surface 56, depresses the nose of the pawl out of engagement with the clutch tooth which is applying theexcessive force.

In this example also'the pawl is of such a shape that the bias of the pawl towards its engaging position is increased by the effect voi' centrifugal force upon rotation of the nut 22|).

The construction shown in Fig. 8 is similar to that shown in Fig. 3, except that the nose of the pawl 25 is provided with an abutting edge 30A, while the tooth |8B is provided with a face portion lll with which this abutting edge co-operates and which is so inclined that excessive torque loading transmitted through the pawl will rock it clockwise out of engagement with the tooth IIB.

I claim:

l. synchronizing coupling means comprising a toothed iirst member, a second member rotatable relatively to said iirst member, an interv mediate member so engaged with said'second member as to be constrained to move helically with respect thereto in consequence of relative rotation between the intermediate and second members, the intermediate member having teeth engageable with the teeth on the first member, and a subsidiary ratchet drive adapted to couple together said iirst and intermediate members and so arranged as to eiect engagement of the teeth of said iirst and intermediate members without clashing on relative angular displacement of said nrst and second members in one sense, said subsidiary ratchet drive comprising means which enable it to slip automatically in consequence o! the application of excessive torque through it and which, when the conditions producing such excessive torque no longer exist, leave the ratchet drive in condition to perform its normal function.

2. synchronizing coupling means comprising a toothed iirst member, a second member rotatable relatively to said iirst member, a toothed intermediate member so engaged with said second member as to be constrained to move helically with respect thereto in consequence of relative rotation between said intermediate and second members, a subsidiary ratchet drive iricluding a pawl carried by one of said toothed members and capable of co-operating with the teeth on the other of said toothed members, said pawl being positioned to guide the teeth with which 1to0-operates smoothly into engagement with the teeth on said one of the toothed members on relative angular displacement of said first and second members in one sense, said subsidiary `ratchet drive including means capable of interrupting the drive therethrough in consequence ot the subsidiary drive torque exceeding a predetermined value.

3. synchronizing coupling means comprising a toothed ilrst member, a second member rotatable relatively to said ilrst member, an intermediate member so engaged with said second member as to be constrained to move helically with respect thereto in consequence oi' relative rotation between the intermediate and second members, the intermediate member having teeth engageable with the teeth on the rst. member in consequence of such helical movement, and auxiliary coupling means comprising a ratchet connection between said toothed members for maintaining their teeth aligned for smooth engagement together when said relative rotation occurs in one sense, said auxiliary coupling means permitting relative rotation of said teeth both when said relative rotation occurs in the othe'r sense, and when said relative rotation occurs in said one sense and said pawl is excessively loaded owing to abnormal restraint vof` movement of said intermediate member.

4. synchronizing coupling means comprising a toothed ilrst member, a second member rotatable relatively to said rst member, an intermediate member so engaged with said second member as to be constrained to move helically with respect thereto in consequence of relative rotation between the intermediate and second members, the intermediate member having teeth engageable with the teeth on the first member, and a V pawl on one oi' said toothed member's for cooperation with a set ot teeth' on the other ci said toothed members and so positioned as to guide said toothed members smoothly into mesh with each other on relative angular displacement of said ilrst and second members in one sense, at least one o! the co-operating surfaces oi said pawl and said set of teeth being so inclined that excessive torque loading transmitted through the pawl will displace it out of engagement with any tooth ot said set.

5. synchronizing coupling means as claimed in claim 4. wherein said pawl is so shaped and mounted that its bias towards its engaging position is increased by the eiIect of centrifugal iorce upon rotation of the one of said toothed members on which said pawl is mounted.

6. synchronizing coupling means comprising a toothed nrst member, a second member rotatable relatively to said iirst member, an intermediate member so engaged with said second member as to be constrained to move helically with respect thereto in consequence of relative rotation between the intermediate and second members, the intermediate member having teeth engageable with the teeth on the iirst member, and a pawl on one of said toothed members for co-operation with at least some of the teeth on the other of said toothed members and so positioned as to guide said toothed members smoothly into mesh with each other on relative angular displacement of said ilrst and second members in one sense, the abutting surface ot the nose of said pawl being so inclined that excessive torque loading transmitted through the pawl will displace it out of engagement with any of the teeth that co-operate therewith.

7. synchronizing coupling means comprising a toothed first member, a second member rotatable relatively to said ilrst member, an intermediate member so engaged with said second member as to be constrained to move helically with respect thereto in consequence of `relative rotation between the intermediate and second members, the

intermediate memberhaving teeth engageable with the teeth on the rst member, and a subsidiary ratchet drive adapted to couple together said rst and intermediate members and so arranged as to effect engagement of the teeth of said first and intermediate members without clashing on relative angular displacement oi said ilrst and second members in one sense, said subsidiary ratchet drive including a ratchet device connected in series with a subsidiary clutch device capable of slipping on overload and of being restored to its normal driving condition only when .g its driving and driven elements are in an angular relationship such that the subsidiary ratchet dri is capable of synchronizing the coupling tee 8. synchronizing coupling means comprising a toothed ilrst member, a second member rotatable relatively to said rst member, an intermediate member so engaged with said second member as to be constrained to move helically with respect thereto in consequence of relative rotation between the intermediate and second members, the intermediate member having teeth engageable with the teeth on the iirst member, and a subsidiary ratchet drive adapted to couple together said first and intermediate members and so arranged as to effect engagement of the teeth of said rst and intermediate members without clashing on relative angular displacement of said iirst and second members in one sense, said subsidiary ratchet drive including a ratchet clutch in sexies with a clutch the two parts of which are urged together by a spring and are provided with cooperating zig-zag serrations having a pitch correspending to the pitch of the teeth of said ratchet clutch.

9. synchronizing coupling means comprising a toothed first member, a second member rotatable relatively to said rst member, an intermediate member so engaged with said second member as to be constrained to move helically with respect theretoin consequence of relative rotation between the intermediate and second members, the intermediate member having teeth engageable with the teeth on the first member, a pawl on one of said toothed members for cooperation with .at least some of the teeth on the other of said toothed members, said pawl being displaceable in the circumferential direction relatively to the said `member on which it is mounted, a spring normally retaining said pawl in engagement with a stop limiting such displacement of the pawl in the direction in which the pawl nose faces. and means for retracting said pawl in consequence of its circumferential displacement in the other di rection.

10. synchronizing coupling means as claimed in claim 9, wherein said spring also serves to rock said pawl into its engaging position.

11. synchronizing coupling means comprising a toothed rst member, a second member, a

toothed third member, said three members being capable of relative rotation, a toothed intermediate member capable of moving axially into engagement with said first and third members alternatively and being so engaged with said second member as to be constrained to move helical- 1y with respect thereto in consequence of relative rotation between said intermediate and second members, a resiliently-biased pawl on one of said rst and intermediate members (3o-operating with teeth on the other of said last-mentioned two members, a resiliently biased pawl on one of said intermediate and third members'co-operating with teeth on the other of said last-mentioned two members, said pawls being so posiy,tioned as to effect respectively the said alternatve engagements of the teeth of said intermedi- .ing so inclined with respect to the line of action of the pawl that the pawl will move to adisengaged position on the occurrence of excessive torque load thereon. f

HAROLD SINCALAIR. 'Y 

